Process for heat setting twisted, bulked continuous filament yarn

ABSTRACT

A multi-step process is disclosed for heat setting twisted, bulk continuous filament (BCF) yarn comprising the steps of developing crimp in the yarn under hot atmospheric air and heat setting the yarn by saturated steam treatment.

FIELD OF INVENTION

The present invention relates to an apparatus and method for heat-setting yarn. More particularly, the present invention relates to an apparatus and method for heat-setting cable twisted bulk continuous filament (BCF) yarn.

BACKGROUND

Background art methods for making BCF yarns for carpets typically include the steps of twisting, heat-setting, tufting, dyeing and finishing. In particular, heat-setting of twisted yarn is an important step in converting BCF yarns to carpets. Heat-setting develops crimp and locks the twist memory in the BCF yarns. The development of crimp and twist memory have a significant impact on yarn bulk and newness retention of finished carpets.

Two types of heating-setting methods are used in continuous heat-setting machines of the background art. The first type uses pressurized steam, which can be saturated or near saturated steam. The most common pressurized steam heat-setting machine in the background art is referred to as a Superba® machine such as that produced by American Superba, Inc.

The second type of heat-setting method uses hot atmospheric air. The most common hot atmospheric air heat-setting machine in the background art is referred to as a “Suessen” machine, or “Power-Heat-Set” machine such as those produced by Power-Heat-Set of America.

The crystalline structure of heat-set yarns and the end use performance of the finished carpets produced from heat-set yarns primarily depend on the heat-setting method used in producing the yarn. It is well understood by those skilled in the industry, carpet yarns produced by hot atmospheric air heat-setting machines (e.g., Seussen) have higher bulk and better stain resistance than carpet yarns produced by pressurized steam heat-setting machines (e.g., Superba®).

It is well understood that the heatsetting method used has a great impact on nylon carpet stain performances. Solution dyed nylon (SDN) carpets made from cationic dyeable polymer and heatset using hot atmospheric air have longer-lived, built-in stain resistance. However, SDN nylon carpets made from cationic dyeable polymer, and heatset with saturated steam, are found to have unacceptable stain resistances.

Currently, the majority of heatsetting machines used are pressurized steam heat-setting machines, such as Superba® machines. It is this commercial environment which plays a part in limiting the use of SDN nylon carpet fiber to only those yarn tufting and processing facilities that will heatset using Suessen, or Power Heat-Set processes.

There have been improved heatsetting processes disclosed in the background art. For example, U.S. Pat. No. 7,073,318 discloses an apparatus and method for texture heat-setting bulk continuous filament (BCF) yarns in hot air heat-setting machines that includes a preheating device/step using a mixture of steam and atmospheric air to preheat a twisted BCF yarn bundle to develop crimp memory and provide cohesion to the twisted BCF yarn bundle.

US Patent publication 2007 0137166 is directed to flow management improvement to the known yarn texturing process, and is directed to devices and methods to accumulate one or more yarns between texturing device(s) and coiling device(s) prior to treatment in a heat-setting chamber.

U.S. Pat. No. 7,543,463 relates to a machine and process for heat setting yarn, principally, but not exclusively, carpet yarn. The machine conditions twisted yarns with saturated steam to increase the crystallinity of the yarn and lock the twist or the crimp into the yarn. The machine is a continuous process machine with yarn entering one end of the machine, moving downstream through the machine and exiting the downstream end properly treated and ready for the next production step.

Therefore, a strong need remains for a heatsetting process and apparatus to treat texturized BCF yarn using pressurized steam that results in the required crimp retention, yarn tip definition and stain resistant properties.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts 24 hr. stain test results for carpet samples made from embodiments of the current invention and comparative examples.

FIG. 2 depicts WAQE stain test results for carpet samples made from embodiments of the current invention and comparative examples.

SUMMARY OF THE INVENTION

The present disclosure relates to processes and apparatuses for heat setting twisted, bulk continuous filament (BCF) yarn. Also disclosed are articles, including carpets, formed from using these processes or apparatuses.

In one nonlimiting aspect of the current invention, a multi-step process is disclosed for heat setting twisted, bulk continuous filament (BCF) yarn comprising the steps of (a) developing crimp in the yarn under hot atmospheric air and (b) heat setting the yarn by saturated steam treatment.

In one nonlimiting embodiment, step (a) is performed under hot air at a temperature in the range from about 140° C. to about 210° C. In one nonlimiting embodiment, the yarn is treated in step (a) for a period of about 3 seconds or greater. In another nonlimiting embodiment, the yarn is treated in step (a) for a period of about 3 to about 7 seconds.

In one nonlimiting embodiment, step (b) is achieved with saturated steam at a temperature in the range from about 110° C. to about 130° C. In one nonlimiting embodiment, the yarn is heat set in step (b) for a period of about 25 to about 60 seconds.

In another nonlimiting embodiment, the yarn is formed from a synthetic polymer selected from the group consisting of nylon, polyester, polyolefin and copolymers and blends thereof. In another nonlimiting embodiment, the yarn is formed from nylon 6,6 or nylon 6 polymer.

In another nonlimiting embodiment, the yarn is made from cationic dyeable nylon polymer. In another nonlimiting embodiment, the cationic dyeable nylon polymer comprises a stain blocking additive capable of disabling acid dye sites in the polymer. In another nonlimiting embodiment, the stain blocking additive is present in a range from about 1 to 10 percent by weight. In another nonlimiting embodiment, the stain blocking additive is an aromatic sulfonate or an alkali metal salt thereof. In another nonlimiting embodiment, the yarn is solution dye nylon yarn.

In another aspect of the current invention, articles are disclosed that are formed from the yarn treated by any of the processes described above. In another aspect of the current invention carpets are disclosed that are formed from the yarn treated by any of the processes described above. In one nonlimiting embodiment, the carpet has a stain rating of 8 or higher according to the 24 hour stain test. In another nonlimiting embodiment, the carpet has a stain rating of 7 or higher according to the WAQE stain test.

In another aspect of the current invention, an apparatus is disclosed for heat setting twisted, bulk continuous filament (BCF) yarn comprising a bulking apparatus configured to bulk the yarn with hot atmospheric air to develop crimp and a heat setting tunnel configured to heat set the yarn by steam injection.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure relates to processes and apparatuses for heat setting twisted, bulked continuous filament (BCF) yarn. Also disclosed are articles, including carpets, formed from using these processes or apparatuses.

In one nonlimiting embodiment, a multi-step process for heat setting twisted, bulked continuous filament (BCF) yarn is disclosed comprising the steps of (a) developing crimp in the yarn under hot atmospheric air and heat setting the yarn from step (b) by saturated steam treatment.

In one embodiment, the twisted, bulked continuous filament (BCF) yarn is texturized prior to step (a). Hot air treatment is an effective process for developing crimp in yarn. In one nonlimiting embodiment, step (a) is performed under hot air at a temperature in the range from about 140° C. to about 210° C. It is understood the hot air treatment may be applied in any method known to those skilled in the art to develop yarn crimp in the BCF yarn. The hot air treatment may be applied for a duration necessary to achieve the desired crimp development in the yarn. In one nonlimiting embodiment, the yarn is treated in step (a) for a period of about 3 seconds or greater. In another nonlimiting embodiment, the yarn is treated in step (a) for a period of about 3 to about 7 seconds.

In order for yarn used in carpets to have the necessary aesthetics and floor performance for residential applications it is necessary to develop tip definition in the tam. In one nonlimiting embodiment of the current invention, tip definition is achieved by treating the BCF yarn from step (a) with saturated steam. In another embodiment step (b) may be performed with pressurized steam at near saturation level. In another nonlimiting embodiment, step (b) is achieved with saturated steam at a temperature in the range from about 110° C. to about 130° C. the steam treatment in step (b) may be for any duration necessary to achieve the desired tip definition. In one nonlimiting embodiment, the yarn is heat set in step (b) for a period of about 25 to about 60 seconds.

Embodiments of the current invention may be performed with yarns formed from a synthetic polymer selected from the group consisting of polyamide, polyester, polyolefin and copolymers and blends thereof.

Nonlimiting examples of polyamide fibers include fibers comprising nylon 5,6; nylon 6/6; nylon 6; nylon 7; nylon 11; nylon 12; nylon 6/10; nylon 6/12; nylon DT; nylon 6T; nylon 6I; and blends or copolymers thereof. Nonlimiting examples of polyolefin fibers include fibers comprising polypropylene. Nonlimiting examples of polyester fibers include fibers comprising polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polylactic acid (PLA) and blends or copolymers thereof.

In one nonlimiting embodiment, the yarn is formed from nylon 6,6 or nylon 6 polymer.

Without being bound any particular theory, it is believed that using pressurized steam treatment to develop yarn crimp prevents the polymer crystal structure in yarns made from polyamides from opening and becoming more susceptible to acid stains. It is well known in that art that this phenomenon prevent the use of most polyamide yarns with built in stain resistance from being used with heat setting processes. Through undue experimentation, the inventors have discovered that using a multi-step process, twisted BCF yarn could be heat set to achieve crimp development, tip definition without opening the polymer structure to the point that the yarn becomes more susceptible to acid stains. The embodiments of the current invention thus allow polyamide yarns with built in stain resistance to be used with heat setting machines that use pressurized steam or saturated steam to create tip definition.

In one nonlimiting embodiment, the yarn used is made from cationic dyeable nylon polymer. As used herein, cationic dyeable nylon polymer are nylon polymers modified to make them receptive to cationic dyes. In one nonlimiting embodiment, the cationic dyeable nylon polymer comprises a stain blocking additive capable of disabling acid dye sites.

Suitable built-in stain blocking additives include those that are known to disable acid dye sites. For examples, in polyamides, such as nylon 6,6 or nylon 6, acid dyes sites refer to amine end groups or amide linkages that react or associate with acid dyes, which results in staining. Stain blocking additives react or associate with these acid dye sites to prevent the acid dye sites from reacting or associating with acid dyes. Suitable stain blocking additives for use in polyamides are discussed in U.S. Pat. No. 5,155,178, herein incorporated by reference. Suitable stain blocking additives include, but are not limited to aromatic sulfonates and alkali metal salts thereof, such as 5-sulfoisophthalic acid, sodium salt and dimethyl-5-sulfoisophthalate, sodium salt. In one nonlimiting, embodiment, the stain blocking additive is 5-sulfoisophthalic acid, sodium salt (SSIPA). In one nonlimiting embodiment, the stain blocking additive is present in a range from about 1 to 10 percent by weight. In another nonlimiting embodiment, the stain blocking additive is present in a range from about 1 to 5 percent by weight.

In another nonlimiting embodiment, the yarn is solution dye nylon (SDN) yarn.

In another aspect of the current invention, articles are disclosed that are formed from the yarn treated by any of the processes disclosed herein. In another aspect of the current invention, carpets are disclosed that are formed from the yarn treated by any of the processes disclosed herein. As shown in examples 2 and 3, in nonlimiting embodiments, carpets are disclosed that have a stain rating of 8 or higher according to the 24 hour stain test. As shown in examples 2 and 3, in nonlimiting embodiments, carpets are disclosed that have a stain rating of 7 or higher according to the WAQE stain test.

In another aspect of the current invention an apparatus is disclosed for heat setting twisted, bulk continuous filament (BCF) yarn comprising a bulking apparatus configured to bulk the yarn with hot atmospheric air to develop crimp and a heat setting tunnel configured to heat set the yarn by steam injection.

Suitable bulking apparatus may be any apparatus known to those skilled in the art that can develop crimp in twisted BCF yarn. In one nonlimiting embodiment, suitable bulking apparatuses include those that utilize circulating hot air to develop yarn crimp. In one nonlimiting embodiment, the bulking apparatus is capable of developing crimp under hot air at a temperature in the range from about 140° C. to about 210° C. It is understood the hot air treatment may be applied in any method known to those skilled in the art to develop yarn crimp in the BCF yarn. The hot air treatment may be applied for a duration necessary to achieve the desired crimp development in the yarn. In one nonlimiting embodiment, the bulking apparatus is capable of developing crimp for a period of about 3 to about 7 seconds.

Suitable heat setting tunnels may be known to those skilled in the art that can develop tip definition in twisted BCF yarn. As used herein, tip definition is defined the level of distinction between the tips of tufts in carpet yarn. Tip definition is considered to be excellent if there is clean tip separation between the tufts. In one nonlimiting embodiment of the current invention, the heat setting tunnel is configured to treat the BCF yarn from the bulking apparatus via pressurized steam injection with saturated steam. In another nonlimiting embodiment, the heat setting tunnel is configured to treat the BCF yarn with pressurized steam at near saturation level. In another nonlimiting embodiment, the heat setting tunnel is configured to treat via pressurized steam injection with saturated steam at a temperature in the range from about 110° C. to about 130° C. The heat setting tunnel may be configured to inject pressurized steam for any duration necessary to achieve the desired tip definition. In one nonlimiting embodiment, the yarn is heat set in heat setting tunnel for a period of about 25 to about 60 seconds.

Embodiments of the current invention may be performed with yarns formed from a synthetic polymer selected from the group consisting of polyamide, polyester, polyolefin and copolymers and blends thereof.

Nonlimiting examples of polyamide fibers include fibers comprising nylon 5,6; nylon 6/6; nylon 6; nylon 7; nylon 11; nylon 12; nylon 6/10; nylon 6/12; nylon DT; nylon 6T; nylon 6I; and blends or copolymers thereof. Nonlimiting examples of polyolefin fibers include fibers comprising polypropylene. Nonlimiting examples of polyester fibers include fibers comprising polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polylactic acid (PLA) and blends or copolymers thereof.

In one nonlimiting embodiment, the yarn is formed from nylon 6,6 or nylon 6 polymer.

In one nonlimiting embodiment, the yarn used is made from cationic dyeable nylon polymer. As used herein, cationic dyeable nylon polymer are nylon polymers modified to make them receptive to cationic dyes. In one nonlimiting embodiment, the cationic dyeable nylon polymer comprises a stain blocking additive capable of disabling acid dye sites.

Suitable built-in stain blocking additives include those that are known to disable acid dye sites. For examples, in polyamides, such as Nylon 6,6 or Nylon 6, acid dyes sites refer to amine end groups or amide linkages which react or associate with acid dyes which result in staining. Stain blocking additives react or associate with these acid dye sites to prevent the acid dye sites from reacting or associating with acid dyes. Suitable stain blocking additives for use in polyamides are discussed in U.S. Pat. No. 5,155,178, herein incorporated by reference. Suitable stain blocking additives include, but are not limited to aromatic sulfonates and alkali metal salts thereof, such as 5-sulfoisophthalic acid, sodium salt and dimethyl-5-sulfoisophthalate, sodium salt. In one nonlimiting, embodiment, the stain blocking additive is 5-sulfoisophthalic acid, sodium salt (SSIPA). In one nonlimiting embodiment, the stain blocking additive is present in a range from about 1 to 10 percent by weight. In another nonlimiting embodiment, the stain blocking additive is present in a range from about 1 to 5 percent by weight.

In another nonlimiting embodiment, the yarn is solution dye nylon (SDN) yarn.

In another aspect of the current invention, articles are disclosed that are formed from the yarn treated by any of the apparatuses disclosed herein. In another aspect of the current invention, carpets are disclosed that are formed from the yarn treated by any of the apparatuses disclosed herein. As shown in examples 2 and 3, in nonlimiting embodiments, carpets are disclosed that have a stain rating of 8 or higher according to the 24 hour stain test. As shown in examples 2 and 3, in nonlimiting embodiments, carpets are disclosed that have a stain rating of 7 or higher according to the WAQE stain test.

The following section provides further illustration of the processes and apparatuses of this invention. These working examples are illustrative only and are not intended to limit the scope of the invention in any way.

EXAMPLES Test Methods

ACID DYE STAIN TEST: Acid dye stain resistance is evaluated using a procedure adapted from the American Association of Textile Chemists and Colorists (AATCC) Method 175-2003, “Stain Resistance: Pile Floor Coverings.” 9 wt % of aqueous staining solution is prepared, according to the manufacturer's directions, by mixing cherry-flavored KOOL-AID® powder (Kraft/General Foods, Northfield, Ill. White Plains, N.Y., a powdered drink mix containing, inter alia, FD&C Red No. 40). A knitted sock (4×6-inch) is placed on a flat non-absorbent surface. A hollow plastic 2-inch (5.1 cm) diameter cup is placed tightly over the test sample, which can be a knitted sock, or a tufted carpet, for example. Twenty ml. of the KOOL-AID® staining solution is poured into the cup and the solution is allowed to absorb completely into the test sample. The cup is removed and the stained sample is allowed to sit undisturbed for 24 hours. Following incubation, the stained sample is rinsed thoroughly under cold tap water, excess water is removed by centrifugation, and the sample is dried in air. The sample was visually inspected and rated for staining according to the FD&C Red No. 40 Stain Scale described in AATCC Method 175-2003. Stain resistance is measured using a 1-10 scale. An undetectable test staining is accorded a value of 10.

WAQE SHAMPOO TEST: Carpeting wash durability was tested by the Shampoo-Wash Durability Test, using Duponol WAQE as detergent, as referenced and described in U.S. Pat. Nos. 5,853,814 and 5,948,480. Each sample tested according to this method was visually inspected and rated for staining according to the FD&C Red No. 40 Stain Scale described in AATCC Method 175-2003.

CARPET DURABILITY TEST: Carpet durability was evaluated based on procedures described in the Vetterman Drum Texture Retention Test (ASTM D5417).

Example 1(Comparative)

A 997 denier Antique White color solution dyed BCF (997-H 2779 by Invista) made from cationic dyeable nylon 66 polymer was first converted into 6.0 twist per inch cable twisted yarns, and subsequently heatset on Superba using different process settings. The cable twisted and heatset yarns were converted into 45 oz carpets for stain and floor performance tests

This item was heatset on Superba using the state of art process. Twelve ends of cable twisted yarns were first processed through the texturing unit, heated with 99° C. atmospheric saturated steam for about 5 seconds in the pre-bulker and set in tunnel with 130° C. pressurized saturated steam for about 60 seconds. The processed yarn was converted into a 45 oz/yd., 19/32 inch pile height cut pile carpet on a 1/10 ga. machine. The tufted carpet was coated with latex to secure tufts using the state of art latexing process. The finished carpet had excellent tip definition.

This item was test for stain and texture retention. It scored a 6 (1 to 10 rating, 10 has no stain) for 24 hour stain resistance, and a 5 for WAQE Shampoo stain resistance. It failed the stain performance requirement for premium carpets. The texture retention was excellent. This item was rated 3.8 (1 to 5 scale) for carpet durability after five thousand cycles in a Vetterman drum.

Example 2 (Current Invention)

Twelve ends of cable twisted yarns were first processed through the texturing unit, heated with 200° C. dry air for about 5 seconds in the pre-bulker and set in tunnel with 115° C. pressurized saturated steam for about 60 seconds. The processed yarn was converted into a 45 oz/yd. 19/32 inch pile height cut pile carpet on a 1/10 ga. machine. The tufted carpet was coated with latex to secure tufts using the state of art latexing process. The finished carpet had excellent tip definition.

This item was test for stain and texture retention. It scored an 8 (1 to 10 rating, 10 has no stain) for 24 hours stain resistance and an 8 for WAQE Shampoo stain resistance. It performed significantly better than the carpet described in Example 1. The texture retention was excellent. It also scored 3.8 (1 to 5 scale) for carpet durability after 5 thousand cycle test in a Vetterman drum.

Example 3 (Current Invention)

Twelve ends of cable twisted yarns were first processed through the texturing unit, heated with 190° C. dry air for about 5 seconds in the pre-bulker and set in tunnel with 115° C. pressurized saturated steam for about 60 seconds. The processed yarn was converted into a 45 oz/yd. 19/32 inch pile height cut pile carpet on a 1/10 ga. machine. The tufted carpet was coated with latex to secure tufts using the state of art latexing process. The finished carpet also had excellent tip definition.

This item was test for stain and texture retention. It scored an 8 (1 to 10 rating, 10 has no stain) for 24 hours stain resistance and a 7 for WAQE Shampoo stain resistance. It performed significantly better than the carpet described in Example 1. The texture retention was excellent. It also scored 3.8 (1 to 5 scale) for carpet durability after 5 thousand cycle test in a Vetterman drum.

Example 4 (Comparative)

Twelve ends of cable twisted yarns were first processed through the texturing unit, heated with 200° C. dry air for approximately 5 seconds in the pre-bulker, and passed through the tunnel in the absence of supplied steam, or hot air. This item was used to pin point the impact of steam in the tunnel on stain and texture retention. The processed yarn was converted into a 45 oz/yd. 19/32 inch pile height cut pile carpet on a 1/10 ga. machine. The tufted carpet was coated with latex to secure tufts using the state of art latexing process. The finished carpet had poor tip definition. It was not an attractive carpet.

This item was tested for stain and texture retention. It scored an 8 (1 to 10 rating, 10 has no stain) for 24 hours stain resistance and a 9 for WAQE Shampoo stain resistance. It performed significantly better than Example 1. The texture retention was acceptable, but not good as previous examples. It scored 3.2 (1 to 5 scale) for carpet durability after 5 thousand cycle test in a Vetterman drum. Although it passed the end use tests, it cannot be sold as a premium commercial product due to poor tip definition. 

1. A multi-step process for heat setting twisted, bulk continuous filament (BCF) yarn comprising the steps of: a) developing crimp in the yarn under hot atmospheric air; and b) heat setting the yarn from step (a) by pressurized steam treatment.
 2. The process of claim 1 wherein step (a) is performed under hot air at a temperature in the range from about 140° C. to about 210° C.
 3. The process of claim 1 wherein step (b) is achieved with saturated steam at a temperature in the range from about 110° C. to about 130° C.
 4. The process of claim 1 the yarn is treated in step (a) for a period of about 3 to about 7 seconds.
 5. The process of claim 1 wherein the yarn is heat set in step (b) for a period of about 25 to about 60 seconds.
 6. The process of claim 1 wherein the yarn is formed from a synthetic polymer selected from the group consisting of nylon, polyester, polyolefin and copolymers and blends thereof.
 7. The process of claim 1 wherein the yarn is formed from nylon 6,6 or nylon 6 polymer.
 8. The process of claim 1 wherein the yarn is made from cationic dyeable nylon polymer.
 9. The process of claim 8 wherein the cationic dyeable nylon polymer comprises a stain blocking additive capable of disabling acid dye sites in the polymer.
 10. The process of claim 9 wherein the stain blocking additive is present in a range from about 1 to 10 percent by weight.
 11. The process of claim 9 wherein the stain blocking additive is an aromatic sulfonate or an alkali metal salt thereof.
 12. The process of claim 9 wherein the yarn is solution dye nylon yarn.
 13. An article formed from the yarn treated by process of claim
 1. 14. A carpet formed from the yarn treated by process of claim
 1. 15. The carpet of claim 14 wherein the carpet has a stain rating of 8 or higher according to the 24 hour stain test.
 16. The carpet of claim 14 wherein the carpet has a stain rating of 7 or higher according to the WAQE stain test.
 17. An apparatus for heat setting twisted, bulk continuous filament (BCF) yarn comprising: a) a bulking apparatus configured to bulk the yarn with hot atmospheric air to develop crimp; and b) a heat setting tunnel configured to heat set the yarn by pressurized steam injection.
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 27. An article from the yarn treated by apparatus of claim
 17. 28. A carpet from the yarn treated by apparatus of claim
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